Freinds truck got a problem

[tractor8]

My freind has a 89'GMC K1500 w/ 5.7. The check engine light comes on when it gets good and hot. Pulled the codes and got a Electronic Spark Control and EGR system malfunction. The truck doesn't seem to have the power it should and sometimes back fires through the intake when you get back on the gas after coasting. It also sometimes stutters on acceleration from a stop. It has been converted to true duals with flowmasters and no cats (SHHHHHH) Does anybody know what could be wrong, the EGR seems to check out O.K. but it could still be the problem.

[Chevyman69]

Trust me your duals have absolutely nothing to do with the problem. Anyone who says duals cause a problem on TBI's does not know what they are talking about. I have owned a 94, 95 and 92 all with true duals. as well friends have a 90, 91 and never had a problem related to the exhaust. If the valve is sticking either open or closed 2 symptoms are present in either situation. Stuck closed the engine will run hot but other than the light not really run differently. If its stuck open the engine will have a poor idle and not run properly untill warmed up and at normal operating temperature. The ESC can be because of a faulty ESC unit( mounted on a bracket in front of the EGR, flat looks like a card with a 4 or 5 pin connector), knock sensor which is in the block on the right side. Sounds more like a ESC module but could be either. On my truck it threw code 42 and 43 and it just ended up being the module in the distibutor, that caused both. Fix the EGR and remember to check vacuum connections and make sure it is hooked up properly and then worry about the other problems.

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69 CST 10, 402, steel crank, heavy rods, Federal Mogul Forged Pistons, 9.9:1 compression, polished ported 781 heads 2.19/1.88 manley stainless valves, Crane Powermax Hydraulic roller 288/296 and .587,.610 lift, hardened pushrods, Crane Roller Rockers, Weiand Action Plus, 800CFM Rochester QJET, MSD HEI, MSD 8MM Wires, should be about 500 H.P. 700R4 2500 stall, pretty nasty shift kit, 373 Auburn Pro Series Posi, buckets/console air/tilt/tach 4wheel discs
Daily Driver: 92 Chev Reg Cab LWB Silverado 4x4, loaded, 350 Accel filter/cap/rotor/coil/AC Delco RapidFire plugs, Edelbrock intake and headers, Hypertech Thermomaster Chip, true duals 700R4 with B@M Shift Kit for now!

[brandonh]

i have a 90 chevy 5.7 and i had the same problems so first i put a new cap and rotor on it and it fixed it then i went driving for a while and it did it again. while it was doing it, the light would come on and then it would sometimes die, when it died the computer would still be telling the fuel injectors to come on. so then i replace the control module and if work for a little while then messed up again, so i put a pickup coil on it and plug wires. That didnt work So i changed my computer(ECM) and it has worked fine "knock on wood". i hope this helps.

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Brandon H
67 chevy CST

[c_lorencz]

My only thought is that your EGR valve is stuck open.

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'84 Sierra: '78 chev SB 400:
Steel crank,Drop forged rods, and pistons,
Crane .477/.481 hyd roller cam
Manley 1.50/1.94 valves
Edelbrock Pro Ram 2 blower intake
underneath dual Holley 390 cfm carbs,
Stock 350 turbo tranny
Daily driver: 94 Pontiac trans sport minivan